1. Field of Invention
The invention relates to a light emitting device and a control method thereof.
2. Related Art
If the liquid crystal display (LCD) device such as a LCD TV or a computer screen uses the light emitting diodes (LED) as the light source of the backlight module, tens to hundreds of LEDs are usually needed. For a better display image with true color, it is important to control the average brightness of the LEDs. Normally, the LCD device includes a LCD panel and a backlight module.
Referring to FIG. 1, the conventional backlight module has a plurality of LEDs 11, a light detector 12, and a controller 13. The light detector 12 detects the brightness generated from each LED 11 and then produces a feedback signal, which is sent to the controller 13, according to the brightness. The controller 13 adjusts the brightness of the corresponding LEDs 11 according to the feedback signal.
However, conventionally the light detector 12 detects the light intensity of the LEDs 11 and produces the feedback signal, and the brightness of the LEDs 11 is then adjusted by the controller 13 according to the feedback signal. As the number of the LEDs 11 increases, the number of the controllers 13 must increase as well hence the cost rises.
Therefore, it is an important subject of the invention to properly control the brightness of the light emitting unit and lower the manufacture cost.